Microwave ovens have become common appliances in most American households. In today's fast paced society, the savings in cooking time that microwaves afford over conventional ovens have made them an appliance of choice for meal preparation. In particular, microwave ovens are most commonly used to reheat foods, to defrost and/or cook frozen prepared and packaged foods.
One of the largest drawbacks in microwave cooking is that foods, even when fully cooked, do not exhibit a fully developed “oven-browned” color. This is a particular problem with microwave cooked pies because consumers expect a pie to have a golden brown color and a certain slightly crispy texture when cooked. Instead, microwave cooked pies tend to have a dull grayish appearance which is generally unpalatable to the average consumer. To overcome these drawbacks, food manufacturers have developed various chemical techniques, food coloring and packaging configurations to help foodstuffs cooked in a microwave achieve a similar golden brown color and crisp texture associated with conventional oven cooking.
The most common reaction responsible for surface browning during cooking is the Maillard reaction (non enzymatic browning) between naturally occurring reducing sugars and compounds containing an amino acid group, e.g. amino acids, peptides and, proteins which results in the formation of colored melanoidins. Maillard reaction rates are increased with an increase in temperature, pH, concentration of Maillard reactants, water activity, oxygen supply, and nature of the raw materials among other factors. When a foodstuff is cooked in a conventional oven, the surface of the foodstuff is heated to considerably higher temperatures than the interior layers of the foodstuff, with the high surface temperatures being sufficient to achieve browning. A number of patents have issued directed to browning agents for foodstuffs having carbonyl-containing components for the browning reaction and, in particular, as microwavable browning coatings including U.S. Pat. No. 4,448,791; and European Patent Application No. 0 203 725 (1986). These patent publications are directed to browning agents and compositions that depend upon the reaction of an amino acid and sugar, especially as the reaction may be catalyzed by the addition of alkali to allow the reaction to take place at lower temperatures.
In microwave cooking, however, heat energy is released internally within the food so that the surface and interior remain at relatively similar temperatures. Consequently, the high surface temperatures necessary to achieve conventional oven type browning are not reached within the time required to cook a foodstuff in the microwave. To achieve the golden brown color of microwave cooking, food manufacturers have generally developed ways to treat the surfaces of various foodstuffs with browning agents. Some of these browning agents are either prereacted or partially reacted and applied like a sauce to foodstuffs to give them a golden brown appearance even before the food is cooked. This effect is enhanced during cooking. Other, more modern browning agents help induce the Maillard reaction at lower temperatures and faster cooking times by adjusting the other variables, such as pH and Maillard reactant concentration, to enhance browning at the surface of a foodstuff during microwave cooking.
An aqueous syrup containing a melted, caramelized, and foamed disaccharide, alone or in combination with a minor amount of monosaccharide has been described as a browning agent for foods cooked in a microwave oven. U.S. Pat. No. 4,252,832. This aqueous syrup is first heated until it produces a dark syrupy composition, mixed with salt, then brushed onto foods such as meats, poultry, fish, cakes, pies, or french-fry cut potatoes to give them a golden brown color even when they are cooked in a microwave.
A browning agent containing food starting materials and at least one carbohydrate having beta configuration has been described for use as a sauce base or meat flavor concentrate. The browning agent is prepared by heating hexose, glucose, or disaccharides having a beta-configuration with a food starting material such as potatoes, milled cereals, meat, bone, milk products, etc. at 100–200° C. for 10–30 minutes. The product undergoes a Maillard reaction during heating and the resulting brown colored browning agent can be used as a starting material for various uses such as a sauce base.
A browning agent containing a water-in-oil emulsion, a surfactant, and an edible base in an aqueous phase has been described for browning foodstuffs having a carbonyl containing browning reactant. U.S. Pat. No. 4,968,522. The emulsion can be coated onto pizza, pot pie doughs, processed potato nuggets (e.g., frozen shredded potatoes sold under the tradename “Tatertots” by Ore-Ida Potato Products, Inc. a division of H J Heinz of Pittsburg, Pa.) and hash browns. The water-in-oil emulsion prevents the edible base from contacting the carbonyl containing browning reactant in the foodstuff until the foodstuff is heated in a microwave or conventional oven. When this browning agent is subjected to heat, the edible base is released from the emulsion causing the pH of the surface of a foodstuff to increase, thereby inducing the browning reaction.
A browning composition for microwave foodstuffs obtained by spray drying a solution containing reducing sugar and milk protein has also been described. U.S. Pat. No. 5,196,219. The browning composition is produced by hydrolyzing an aqueous solution of milk solids, such as skim milk, evaporated skim milk and reconstituted non-fat dry milk, with lactase enzyme to convert substantially all of the lactose in the solution to glucose and galactose, and spray drying the hydrolyzed milk solids solution. During spray drying, Amadori rearrangement products, which are intermediary compounds in the formation of colored Maillard reaction products, are formed in the spray dried product. The spray dried product is reconstituted with water and coated onto the surface of a foodstuff, preferably the uncooked dough crust of a meat or fruit pie. Upon heating the coated foodstuff with microwave radiation, a desirable browned surface is developed on the crust during the time normally required to bake the pie, due to the formation of colored Maillard reaction products in the coating composition at microwave temperatures.
A bottom crust for a pie having a raw dough base containing a reducing sugar and an amino acid source to induce a Maillard-type browning reaction and caramelization browning during microwave exposure has also been described. U.S. Pat. No. 4,917,907. A preferred bottom crust contains a reducing sugar such as dextrose, an amino acid source such as whey solids, a dough conditioner to prevent dough shrinkage and a leavening agent to enhance browning and to provide a puffy crust. Pies made with this bottom crust are placed into a tray which is composed of a microwave-interactive material. Maillard-type browning reactions occur upon exposure of the bottom crust dough to microwave energy which causes water in the dough to become heated which in turn causes the dough to become heated. Caramelization browning reactions occur due to heat conducted from the tray into the bottom crust dough, which additionally gives the dough a crispier texture. A pie made with this bottom crust may also comprise a top crust dough. The top crust dough preferably has a laminate structure comprising a conventional dough coated with a reactive dough of a composition similar to the bottom crust dough.
Currently available browning agents and products containing browning agents have greatly increased the palatability of microwave cooked foodstuffs. There is a need, however, to improve the appearance, texture, and taste of microwaveable foodstuffs even further. This need is particularly felt in the area of frozen meat pies, one of the most commonly purchased frozen food items in the United States. Meat pies, commonly known as pot pies, require a long amount of time for proper conventional oven cooking, making the microwave a preferred option for cooking this foodstuff. Unfortunately, even with the various browning agents and additives currently being added to make pot pies more appetizing out of the microwave, most microwaved pot pies have a less appetizing dough color, texture, or flavor than those cooked in a conventional oven.
The present state of the art demands further improvements to be made in browning agents. Browning agents are needed that do not introduce an undesirable flavor into the foodstuff being browned. There is a definite need for foodstuffs containing browning agents that look attractive and yet may be quickly heated and browned even under the most demanding conditions of microwave ovens.